A number portability (Number Portability, NP for short) service is a service that a user is capable of continuing to use an original number in a currently subscribed network after the user changes a subscription network. By using the NP service, the user is capable of changing the subscription network very conveniently. Currently, for fair competition, the Telecommunications Regulatory Authorities in many countries and regions require all telecom operators to provide the NP service, so as to avoid inconvenience caused due to a change in the number required after the user changes the subscription network.
A network to which the user currently subscribes is also known as a recipient network (Recipient Network), and a network to which the user initially subscribes is known as a donor network (Donor Network). For example, for a UE (User Equipment, user equipment) whose number is xxx, a donor network to which the UE belongs is a communications network deployed by China Mobile; when the user is ported in (port in) a communications network deployed by China Unicom from the communications network deployed by China Mobile, a recipient network to which the UE belongs is the communications network deployed by China Unicom. In this case, all services on the UE are provided by the communications network deployed by China Unicom.
In IMS (Internet Protocol Multimedia Subsystem, Internet Protocol multimedia subsystem) network architecture, when a called UE has changed a subscription network and subscribed to an NP service, in a process in which a calling UE calls the called UE, a calling network side first needs to perform charging authentication for the calling UE, then query a routing number (Routing Number, RN for short) corresponding to a number of the called UE in a number portability database (Number Portability Database, NPDB for short) server after the charging authentication is successful, and route the call to a recipient network to which the called UE belongs according to the routing number obtained through the query. The calling network side refers to a communications network to which the calling UE belongs. When the called UE has changed the subscription network and subscribed to the NP service, the called UE may use a number allocated by a donor network in the recipient network.
Specifically, after receiving a call request sent by the calling UE, an S-CSCF (Serving-Call Session Control Function, serving-call session control function) entity at the calling network side sends an initial CCR (Credit Control Request, credit control request) message to an OCS (Online Charging System, online charging system) at the calling network side through an AS (Application Server, application server) at the calling network side. The initial CCR message carries a number of the calling UE and the number of the called UE. The OCS determines a communications network to which the called UE belongs according to the number of the called UE, determines a charge rate of a call between the communications network to which the calling UE belongs and the communications network to which the called UE belongs, and performs the charging authentication for the calling UE according to the charge rate, so as to determine whether an account of the calling UE has a sufficient balance to support a call with a minimum call duration. After the charging authentication is successful, the OCS sends a GSU (Granted Service Unit, granted service unit) to the AS. The AS instructs the S-CSCF entity to query the routing number corresponding to the number of the called UE in the NPDB server. After finding the routing number corresponding to the number of the called UE, the S-CSCF entity routes the call to the recipient network to which the called UE belongs according to the routing number.
By analyzing the prior art, the inventor thinks that the prior art at least has the following problem:
In a process in which the calling UE initiates a call to the called UE, the OCS determines the communications network to which the called UE belongs according to the number of the called UE. If the communications network to which the calling UE belongs and the communications network to which the called UE belongs are communications networks deployed by a same operator, charging authentication is performed for the calling UE according to a charge rate of an intra-network call. If the communications network to which the calling UE belongs and the communications network to which the called UE belongs are not communications networks deployed by a same operator, charging authentication is performed for the calling UE according to a charge rate of an inter-network call. For the called UE that has changed the subscription network and subscribed to the NP service, although the number of the called UE does not change, the communications network to which the called UE belongs has changed. Therefore, an error is likely to occur when the OCS performs charging authentication for the calling UE.